Conventionally, containers made of synthetic resin that are compactly collapsible have been known.
Patent Document 1 (Japan Patent Pre-Publication No. H6-312734) discloses “a collapsible container made of synthetic resin including an integrally molded side wall portion and bottom wall portion and provided with a pair of side wall portion fold lines positioned on a plane passing through a container axis and a bottom wall portion fold line positioned on the plane, and where, at a connection portion of the side wall portion and the bottom wall portion, a pair of ground-contacting lower end edges are formed symmetrically with respect to the plane, the bottom wall portion fold line is made up of an apex or an apical side positioned slightly above the lower end edges and a pair of sides connecting the apex or apical side to the side wall portion fold line in a V-like shape or U-like shape, and fold lines are formed respectively between an end portion of the lower end edge and a side wall portion fold line-bottom wall portion fold line connection portion and between the end portion of the lower end edge and bottom wall portion apex or apical side.”
However, with the art disclosed in Patent Document 1, folding or bending is difficult at portions besides portions of the “fold lines” provided at the side wall portion and the bottom wall portion and the container thus cannot be collapsed freely and its size reduction in the collapsed state is not sufficient. Also, collapsing must be performed at the priorly provided “fold line” portions and not only are time and effort thus required for a collapsing process but time and effort are also required for a process of restoration from the collapsed state to a state (usage state) enabling filling with a liquid, etc.
Patent Document 2 (Japan Patent Pre-Publication No. 2010-275012) discloses “a collapsible portable bottle in which an overlappingly folding portion is provided at a side surface of a barrel portion of a bottle, a collapsing portion is provided at an upper portion, a gusset portion is provided at a bottom, and a fastening portion is provided at an appropriate location of a main body of the bottle.”
However, the art disclosed in Patent Document 2 has an arrangement that is collapsed by folding at the “overlappingly folding portion” or the “collapsing portion” provided at the side surface of the bottle barrel portion or the bottle upper portion, and as with Patent Document 1, the container cannot be folded freely and its size reduction in the folded state is not sufficient. Also, collapsing must be performed by folding at the priory provided “overlappingly folding portion” or “collapsing portion” and not only are time and effort thus required for a collapsing process but time and effort are also required for a process of restoration from the collapsed state to a state (usage state) enabling filling with a liquid, etc.
Patent documents are as set bellow.
[Patent Document 1] Japan Patent Pre-Publication No. H6-312734
[Patent Document 2] Japan Patent Pre-Publication No. 2010-275012